1. Field of the Invention
This invention relates to a portable, manually operable dispenser for use with stretch wrap film that is particularly useful for wrapping roll goods.
2. Description of the Prior Art
Stretch wrap film has enjoyed increasing use in all forms of packaging. Stretch wrappers are now applied to unify or contain boxes, bales, sacks, mixed loads, or even a plurality of items of non-uniform shape, such as axe handles. Stretch wrap film is also commonly used to secure a plurality of containers on a pallet. Examples of such uses for stretch film appear in U.S. Pat. Nos. 3,495,375 and 3,867,806. The advantages of using stretch wrap film include its stength despite its lightness, good holding ability, relatively low cost, freedom from the need to use tape or adhesive, and toughness.
Stretch wrap machinery for applying the film ranges from small hand-held devices to very expensive, fully automatic turntable units. Each of these devices is intended for use in applying one or more layers of a thin stretchable film about a load in order to unite it or, to use the industry term, "unitize" it.
For efficient film usage, any device used for film application must include some means for controlling the tension on the film as it is applied. Some large automatic pallet wrapping machines include a core type brake system consisting of a friction element inserted in the hollow core of a film roll. Such a mechanism controls the amount of tension or pull that is applied to the film as the pallet load is unitized. There is also available a surface controlled tension device that features a reduced level of tension initially. For best results, the tensioning mechanism should assure consistent film application so that there is efficient film usage plus flexibility in unitizing loads of different shapes, sizes and weights.
Generally, stretch film machinery that does not offer some form of tension control requires manual adjustment of the tension on the film roll as the film roll decreases in size or as load requirements demand.
Past developments in braking mechanisms for stretch film machinery are represented by U.S. Pat. Nos. 2,655,776; 2,914,893; 4,102,513 and 4,166,589. The latter two of these patents disclose hand-held plastic film wrapping dispensers with friction brake means for controlling the tension on the film during the wrapping operation. In U.S. Pat. No. 4,102,513, adjustment of a threaded member applies or releases braking action. In U.S. Pat. No. 4,166,589, the brake is operated by a cam action. In these hand-held devices, the braking action requires a manual rotary movement by the operator, who is simultaneously holding the device and the film roll, guiding the film so that it is applied over the desired path, and orienting the device as necessary for the job. Considerable dexterity and strength are required.